T-connectors for coaxial cables



July 10, 1956 R. s. CARR Em 2,754,487

T-CONNECTORS FOR COAXIAL CABLS Filed March 14, 1952 2 Sheets-Sheet 1fzz// mmf/cm@ @0m/v6 M/ July 1o, 1956 R. s. CARR Em 2,754,487

T-CONNECTORS FOR COAXIAL CABLES Filed March 14, 1952 2 Sheets-Sheet 2 gjN @x ,SN

Unite ttes Patent T-CONNECTORS FOR COAXIAL CABLES Robert S. Carr,Summit, and Tore N. Anderson, Mountainside, N. J., assignors toAir-tron, Inc., Linden, N. J., a corporation of New Jersey ApplicationMarch 14, 1952, Serial No. 276,636 2 Claims. (Cl. 339-402) Thisinvention relates to which are T-shaped so that, when connected to a setof coaxial cable contacts in a connection plug on a panel, the conectorsarms which form the top of the T will lie close to the panel, thus beingneat and occupying a minimum of space in front of the panel. Theinvention, further, comprehends improved methods of making suchT-connectors.

An important object of the invention is the provision of such aT-connector which is simple and relatively inexpensive to produce.

Another important object is the provision of such a connector having arelatively high corona level.

Another important object is the provision of such a connector havingparts which may be very easily assembled.

Another important object is the provision of an improved method ofmaking such a connector.

The foregoing and other objects are realized by the present invention;and one of numerous embodiments of T-connectors according to thisinvention is shown, for illustrative purposes, in the accompanyingdrawings in which:

Figure l is a central, axial sectional View of a T-connector accordingto a preferred form of this invention, shown in partial association withrelated jack, panel and cable parts.

Fig. 2 is a sectional view substantially on the irregular line 2 2 ofFig. l.

Fig. 3 is a fragmentary sectional view substantially on the line 3-3 ofFig. l.

Fig. 4 is an exploded View of the components of the T- connector ofFigl; most of said components being shown in elevation and some of thembeing shown in section or with parts broken away to show details.

The illustrated T-connector, generally designated 10, if considered onlyas to its essentials, consists of an outer, T-shaped shell 12 ofsuitable conducting metal, an inner, T-shaped conductor 14 and apreferably unitary, T-shaped dielectric sleeve 16, preferably ofrelatively soft silicone rubber, extending between the shell and theinner conductor. Additionally, as hereinafter detailed, there arevarious threaded sleeves and other parts associated with the shell 12for connecting the latter both mechanically and electrically with theouter conductor or conductors of one or more related lengths of coaxialcable and with a jack to which another length of coaxial cable isconnected.

At the lower extremity of the central member of the T-connector(locations being hereinafter recited relatively to the position of thedevice in the several figures of the drawing), the latter is designedand arranged to be connected like a plug to a jack assembly 18, whichmay be fixed to a panel or instrument wall 20 having contacts facingtoward the outer side of the panel or instrument wall (toward the top ofthe latter as shown in the drawing). The jack assembly may have acoaxial cable 22 associated therewith; the conducting portions coaxialcable connectors 2,754 le? Patented July l0,

3 HCC of the cable being mechanically and eelctrically connected toconducting portions of the jack assembly.

At one or both upper-outer extremities of the T-connector, a separatelength or lengths of coaxial cable 24 may be mechanically andelectrically connected to the connector. Such connections, ordinarily,would be similar at both such extremities; hence, it should suilice toshow in detail and to hereinafter describe only an adjacent end of sucha length of coaxial cable connected to the upper-right extremity theconnector.

As illustrated in Fig. l, the jack assembly 18 is a female connectionand the lower end or center arm of the T-connector is a male connectionwhich may be plugged or unplugged quickly relatively to the jackassembly. The outer ends of the top of the T-connector are femaleconnections to which coaxial cables may be more or less permanentlyconnected as hereinafter described.

The jack assembly 18 comprises a cylindrical metal shell 26, whichextends through a circular opening 28 in the panel or instrument wall2t), and is formed with an outer abutment ilange 30 which engages acircular marginal portion of one `side of the panel 26 surrounding thementioned opening therein to locate the shell 26 correctly in place inthe panel; and a lock-nut 32, threaded upon an outer threaded portion 34of the shell 26, locks the latter rmly in its desired relationship tothe panel. The cable 22 is connected to jack assembly 18 similarly tothe connection of cable 24 to the top of the T-connector, all ashereinafter described.

The shell 26 constitutes an outer conductor of the jack assembly 18. Theinner conductor of the jack assembly may be in the form of a femalecontact element 36 having spring contact fingers 38 surrounded by ametal sleeve 39, which is interiorly tapered or beveled at its upper endas at 39a to aid in guiding a contact pin of the connector into placewithin the said lingers. The lower end of the contact element 36 issuitably soldered to the bared end of an inner conductor 40 of the cable22. The contact element 36, together with the mentioned end portion ofthe inner conductor 40 of the cable 22 and an adjacent end portion of adielectric sleeve 42 of said cable, extends coaxially within adielectric sleeve 44 disposed within the shell 26 and held againstaccidental dislodgment therefrom by suitable means, as, for example, bya split snap ring 46 which seats within an internal annular groove 48formed within the shell 26 and extends at least partially into an outercircumferential recess 50 in a locking ring 52 which encircles and isembedded in the dielectric sleeve 44.

The dielectric sleeve of the jack assembly preferably is formed ofrelatively soft silicone rubber, and the dielectric sleeve i2 of thecable may be of a similar material, although, in the cable, it may beadvantageous to employ a somewhat harder material formed of apolyethylene composition.

The pshaped inner conductor 14 comprises an upright, conducting metalrod 54, the lower end of which is reduced to form a Contact pin 56 andthe upper end of the rod Se is reduced and threaded, as at Si?, toenable it to be screwed into a body or central portion 6b of a double,female, conducting metal contact element 62, the opposite ends of whichare similar and are each formed with spring contact lingers 64 forgripping therebetween a contact pin 66 suitably soldered to the end ofan inner conductor 63 of a cable 24. Disposed protectively about thecontact fingers 64 are cylindrical metal sleeves 7l) which areinteriorly tapered at their inner ends, as at 72, to enable them toengage tightly with the central portion 60, and are similarly tapered,as at 74, at their outer ends to facilitate entry of the contact pin 66into rm contacting association with the lingers 64.

The outer extremities -of the top part of the metal shell 12 are formedwith small, inwardly extending fianges 76 to aid in holding the top partof the dielectric sleeve 16 against material endwise shifting.

The .central leg of the dielectric sleeve 16 :extends through andprotrudes from the lower end of ametal supplemental sleeve 78, the upperend of which is threaded into and welded or soldered to a collar 80; and.the upper portion of said collar is shaped complementally -to the toppart of the shell 12 and suitably soldered or welded to the latter toconstitute the collar as an integral shell portion. The supplementalsleeve 78, of course, becomes an integral part .of the shell after beingsoldered `or welded as above described.

The Asupplemental sleeve 7S is formed with an external annular recess 82near its lower end to Areceive .therewithin the Afree ends of springfingers 64 of Ia more or less cylindrical spring S6 having an upperlfinger-bearing base portion 68 in the form of a circular band whichencircles .the supplemental sleeve 7S :and seats thereon .immediatelybeneath an 'outer radial ilange .90 of said supplemental sleeve. Thebase portion or band 8S preferably is welded -.or soldered tothesupplemental sleeve, care being taken, however, that the :spring fingers134 are left free .to flex. As may best :be understood Afrom Figs. 1 and2, the spring fingers S4 diverge slightly outwardly from the baseportion 88 toward their lower or free ends, and .said free ends areindividually -bent inwardly `to seat within the recess S2.

A flanged nut 92 is provided for holding the T-connector positively linconnected or plugged-in association with the jack 1S. This nut isinternally threaded, as at 94, at its lower end to enable it to bescrewed upon the threaded portion 34 of the jack 18. The upper end ofthe nut 92 has an inwardly extending radial ange'96 which terminatesinwardly in close but, nevertheless, sliding association with the outer`surfaces of the collar 8i) and of the supplemental sleeve 78.Surrounding said collar and sleeve, and within the nut 92, are disposeda plurality of alternately arranged, at metal washers 98 and bent springwashers 196. When the nut 92 is screwed down tightly upon the jack 1S,the mentioned assembly of washers .is compressed axially, therebyholding Vthe, T--connector firmly in place in the Vjack with theContactV pin 56 of the inner conductor of said kconnector firmly engaged,for electrical contact within the spring contact fingers 3S of thecontact element 3.6 provided in the jack 18.V lIt maybe observed fromAFig. -l that the inside diameter of the upper end of the jack shell 26is slightly less than the outside diameter of the spring 86 at Vthedivergent portions .of the latters fingers; thus, when lthe lconnectoris plugged into the jack, the spring fingers 84 yieldably Contact theshell 26 and maintain a positive electrical connection between thelatter shell and the shell 12 .of the T-connector.

Except for the .fact that .the inner conductor 68 of cable 24establishes connection with a female contact of the T-connector whilethe inner conductor dll of cable 22 establishes connection with a malecontact of said vconnector, the means by which the cables 22 and 24 maybe associated with ,the connector may be substantially identical and,therefore, it should be understood that the following description ofVthe manner in which cable 24 is connected to .the toppart of :the'T7-connector should serve also as a description of the manner in whichthe cable 22 is connected Vto the. jack 18.

Means for mechanically and -electrically connecting the cable 24 to anupper extremity `of the T-connector vmay comprise an annular, metalconducting sleeve 162, within an outer annular rabbet 104 of which isdisposed, and' preferably soldered, a trimmed end of an outer conductor166 of the cable 24, which conductor 'is usually in the form of a braidof Vseveral plies of conducting metal'wire.

A first clamping ferrule 108 is threaded into one end of a cylindricalclamping sleeve 110, the other end of which is threaded upon an adjacentouter end portion of the 513911.12.; this arrangement serving as a meansfor drawing the inner end of the ferrule 10S against an outer marginalportion of the rabbet 164- to force the inner, preferably conical orspherical, end of the conducting sleeve 102 into firm seating andelectrical contacting engagement with the radial end flange 76 formed onthe adjacent end of the shell 12.

The fermle 1118 toward `its outer end is for-med ywith an inner annularrabbet 112 forming an acute recess which receives therewithin a taperedinner end of a relatively soft rubber clamping ring 114. A secondclamping yferrule 116 is formed with a cylindrical portion 118 which maybe threaded upon the outer end of the ferrule 108, and with an inwardlyextending end flange 12) which abuts the outer end of a washer 122 whichis disposed between the flange 120 and the adjacent outer end of therubber clamping ring 114.

When the ferrule 116 is threaded tightly upon the ferrule 108, theywasher 122 is forced axially inwardly so that its tapered end 124engages the adjacent complementally tapered end of the rubber clampingring 1141. T'hus, :the ring 114 is squeezed between the acute or angularwall `of the rabbet 112 and the tapered inner end of the washer 122,thereby causinU the clampingring to become deformed radially inwardlyinto a very firm clamping engagement with an adjacent portion of anouter insulating jacket 126 ofl the cable 24. lt will be seen that, bythe several ferrules and other parts-just described, the cable is heldfirmly against unintended dislodgment from its connected relationshipwith the upper part of the T-connector. With the parts thus heldtogether, the outer conductor 166 of the cable is held in firmconducting connection, through conducting sleeve 102, with the shell 12which constitutes the outer conductor of the T-connector, while theinner conductor 63 of the cable is maintained in firm conductingconnection, through contact pin 66, with the inner conductor 14 of theT-connector.

iin-connecting the end of the cable 24 to the T-connector, the secondclamping ferrule 116, the washer 122, the rubber clamping ring 114 andthe first clampingA ferruleflibS yare slid onto the free end of saidcable approximately in their relationships shown in Fig. l. Then, at thefree end of the cable, the latters insulating jacket 126 :and its outerconductor 106 are stripped back to some extent to expose the dielectricsleeve 128 of the cable; then the vlatter vis stripped away forA a shortdistance to enable the inner conductor 68 of said cable to be insertedin and soldered to the contact pin 66. The cutting back of the 4outerconductor 166 and of the insulating jacket 126 :should be approximatelyto the extent indicated in Fig. l in order to leave a substantial,exposed endY portion ofthe-dielectric sleeve 12S to telescopewithinjthre endof the top-part of the T-shaped dielectric sleeve of theconnector.

Preferably after the contact ,pin 66 has been soldered to the end of theinner conductor 68, the metal conducting `sleeve '102 is slid vonto andalong the dielectric sleeve 128, and its small-'diameter end is forcedbetween the last-mentioned dielectric sleeve and the outermost end oftheouter conductor 166 of the cable to such anextent that the-fend of saidouter conductor seats within the rabbet '11M-:in -the conducting sleeve.

The outer conductor preferably is soldered in place about and upon thesleeve 12; Then the contactv pin 66=ancl the `adjacent end portion oftheinner conductor 68 of the cable land the surrounding exposed portion ofthe dielectric sleeve '12,8 ofthe cable are pressed forcibly into theadjacent end portion of the upper outer extremity of the T-shapeddielectric sleeve` 16 of the connector until the Contact pin 66 entersbetween and is Vfirmly gripped in electrical contact by theiingers V64.A suitable lubricant such as silicone grease may be appliedto,..said.;ex;

posed portionof the dielectric sleeve 12.8 to facilitate ther armas?introduction of the latter into the dielectric sleeve 16 and to providea tight, voidless t therebetween.

Assuming that the stripping of the cable has been done to the properextent, the large end of the conducting sleeve 102 then will be in firmcontact with the metal shell 12 at the latters radial flange 76. Withthe parts in the relationship just mentioned, the ferrules 108 and 116may be drawn up tightly to hold the cable firmly in its connectedrelationship with the shell 12 and to expand the soft rubber clampingring 114 radially to cause it to firmly grip the insulating jacket 126of the cable 24.

We have shown in our copending applications Serial No. 199,944, tiledDecember 9, 1950, now Patent No. 2,698,353, dated December 28, 1954,relating to electric cables, and Serial No. 257,276, filed November 20,1951, now abandoned, relating to elbow connectors for coaxial cables,that a high-corona voltage level may be imparted to and maintained in acable and in connectors for cables by coating the inner surface of adielectric sleeve, which immediately surrounds a metal conducting core,with a thin, fluid, conducting compound, thereby assuring asubstantially continuous and extensive electrical contact between saidcore and sleeve. Both of said copending applications also show that themaintenance of a high-corona voltage level in cables and connectors isaided, where the cables are srs-called coaxial cables and where theconnectors are designed for connecting such coaxial cables, by similarlyapplying the thin, fluid, conducting compound to the outer surface ofsuch a dielectric sleeve where the latter is in face-to-facerelationship with a surrounding outer conductor of a coaxial cable or asurrounding shell portion of a connector which functions as an outerconductor. The principle, as disclosed in the mentioned copendin gapplications, may be employed advantageously in T-connectors such asherein disclosed. Although a variety of conducting fluid compounds maybe utilized in this relation, nevertheless, a conducting lluid compoundthat has served satisfactorily as a means of maintaining a high-coronalevel in the connection is one which is made by mixing powdered graphiteand silicone, to which is added sufficient toluol to reduce the mixtureto a very thin liquid approximately of the consistency of water.

The silicone referred to is a recently developed cornposi tioncomprising silica, reacted by molecular rearrangerent to render itdispersible in solvent. It is in the nature of a relativelynon-electric-conductive silicon varnish which was developed primarily asan insulating medium that could be applied in fluid form to parts to beinsulated. Several purposes of the silicone in the present invention areto serve as a medium for holding the graphite in suspension in thetoluol, also as a more or less fluid vehicle for the graphite uponcomplete or partial evaporation of the toluol, and as a means ofcontrolling the concentration of graphite whereby to control theconductive characteristics of the fluid, conducting coating.

lt has been found that satisfactory results are derived in practicingthis invention where approximately equal parts by weight of silicone andgraphite are used. As substances other than silicone and powderedgraphite may be employed in the stated manner and for the statedpurposes, reference is sometimes hereinafter made to a fluid suspensionvehicle as referring broadly to any fluid medium which functions for thestated purposes in association with graphite or an equivalent conductivepowdery substance, and the term conductive powdery substance is employedherein as referring broadly to any powdery substance which functions forthe stated purposes in association with a fluid suspension vehicle.

As it would be practically impossible, because of the thinness of suchfluid composition coating, to show it satisfactorily in the drawings, itis considered desirable to state that such a fluid compound would form asubstantially continuous coating within the several dielectric sleevesof the T-conriector and of the cables connected therewith. The fluidcomposition on such inner, dielectric sleeve surfaces, as consideredfrom the right end of Fig. 1, would maintain contact and substantiallyfill any spaces between said inner sleeve surfaces and the outersurfaces of the inner conductor 63 of cable 24, the contact pin 66, thecylindrical metal sleeve 7f3, the upright rod 54, the metal sleeve 39,the female contacting element 36 and the inner conductor di; of thecable 22. The liuid composition, of course, is similarly located in theupper left arm of the T-connector and the cable which is connected tosaid arm.

Again proceeding from the upper right end of Fig. l, the lluid,conducting composition applied to the outer surfaces of the severaldielectric sleeves would also be contact with the inner surfaces of theouter conductor of the cable 24, conducting sleeve lllZ (as well as theouter end surface of said sleeve), the top or main portion of the metalshell 12, the collar du, the supplemental metal sleeve 7S, thecylindrical shell 26 of the jack assembly and the conducting sleeve andouter cable conductor which, in relation to the jack assembly,correspond to the parts .lttZ and 1&6 just enumerated.

The manufacture of T-connectors of the character disclosed in thisapplication obviously presents some dilliculties. These diiliculties,however, have been overcome by methods substantially as will now bedescribed.

The principal difficulties arise in relation to the disposition of theTshaped dielectric sleeve 16 within the T-shaped metal shell 12 and inthe disposition of the T-shaped inner conductor 14 within the saiddielectric sleeve. According to the present invention, ythe Icollar 8l?is first welded to the top part of the metal shell 12 in which, ofcourse, has previously been cut an opening to coincide with said collar,so that said top part of the shell opens directly into the collar andother parts associated therewith.

After the collar Sil has been welded to the top part of the metal shell,the thus-integrated parts are placed within a mold, which, with the saidintegrated parts, will define a cavity of the same size and shape as thedielectric sleeve 16 to `be formed. Suitable core elements, of course,are associated with .the mold to provide the central T-shaped passage inthe dielectric sleeve. The dielectric sleeve 16 is then molded in place.

After removal of the partial shell and dielectric sleeve 16 from themold, a thin coating of the hereinbefore described lluid, conductingcomposition is applied to certain surfaces of said dielectric sleeve.The said conductl, ing compound may be introduced between said sleeveand surrounding interior surfaces of the shell `by being injectedbetween the sleeve and shell by a pressure needle such as a hypodermicneedle or its equivalent; lthe needle being properly directed throughthe opposite open ends of the metal shell and/or at the bottom of thecollar 80. It has been found, however, that the said fluid, conductingcompound may be advantageously pumped into place Vbetween the shell andthe dielectric sleeve by using a pressure fluid pump or gun fitted withan annular adapter which can be attached to one end of the top part ofthe metal `shell 12. Fluid, conducting compound thus directed betweenthe `dielectric sleeve and 'the shell, toward one end thereof, movesunder pressure entirely to the opposite end of the shell and to thebottom edge of `the collar Sil. Said compound may then be applied in anysuitable manner, as by brushing, to the end faces of the dielectricsleeve 16 at its opposite top ends and to the exterior of the uprightpart of said sleeve; avoiding, however, the application vof the saidcompound to the bottom end face 16a of said sleeve.

After the outer surfaces of the dielectric sleeve are coated, as justdescribed, separate, similar, round man drels or plugs are pressed intoopposite ends of the cavity then existing in the top part of thedielectric sleeve. These mandrels or plugs are extended into thedielectric sleeve to -thesame kextent @as thedielectric sleevesofrelated cables V24 will extend in a Afully .assembled-connec tor andrelated cables. With :the ends of 'the top -part of the sleeve 16 thusplugged, itmay then be inverted and some of the mentioned uid,conducting compound poured into the cavity in said sleeve, after whichthe excess conducting compound material is poured out. Any of saidcompound which becomes deposited upon the llower end 16a of the saiddielectric sleeve is then wiped or otherwise cle-aned away as it isdesired that there be a good dielectric engagement between said endsurface and the opposed end face 44a of the dielectric sleeve of thejack assembly 18. By making 'the surface 16a convex -as best shown inFig. l, it presses iirrnly and completely upon lthe surface '44a whenthe two mentioned sleeve portions are pressed together by tightening ofthe nut 92.

After excess conducting compound has been poured out as just described,the shell and dielectric sleeve assembly is heat-treated as by baking toset the said compound, which 'thereby becomes more or less ltacky. Tobring about this condition where the said .compound is of the characterhereinbefore described, the baking may be conducted at about 150centigrade for from six to ten hours or overnight. After such -heattreatment, the mandrels or plugs are removed.

After removal of the mandrels .or plugs, the double female contactelement 62 is pushed into its proper position from one top vend of thedielectric sleeve 1.6, after which the upright rod 54 is inserted fromthe bottom end of said sleeve and threaded into the contact element 62.The cylindrical metal sleeves '7.9 may then be pushed into place fromopposite top ends of said dielectric sleeve. If desired, the sleeves 70may be properly assembled with the contact element 62 before-the latteris pushed into said dielectric sleeve and the said sleeves and Contactelement may be simultaneously pushed into place as a unitary assembly.

Preferably before the rod 54 is inserted, the supplemental metal sleevewith the spring 86, washers 98 and 100, and vthe flanged nut 92 properlyassociated therewith as shown in Fig. 1, may be threaded into the collar80 and welded thereto or otherwise held against becoming unthreadedtherefrom.

The-completion; of an assembly of the T-connector with the jack assembly1,8 and -with cables 24 has already beenjfullydescribed.

It should be -apparentfrom `the foregoing that av T-connector as hereindisclosed fulfills all the stated objects of this invention; and,lfurthermore, that the inventive concept may be embodiedin variousvstructures other than the single illustratedv embodiment without,however, dcparting from the invention as defined in the followingclaims.

We claim:

1. A T-connector for coaxial cables comprising a rigid, T-shap-ed,electrically conductive, metal, outer shell, a T-shaped dielectricsleeveof pliant insulating material, a T-shaped inner conductor member havingT-constituting portions with outside diameters slightly greater than thelnormal inside diameters of adjacent sleeve portions, the pliancy of thesleeve material being such as to permit `said T-consti'tuting portionsof the inner conductor member to 'be inserted endwise into said sleeveinV intimate association therewith, and a semidiuid, conductive coatingbetween and in contact with said slee-ve land inner conductor member;said conductive coating consisting essentially of sil-icone varnish,powdered graphite and toluol.

2. A T-connector according to claim 1, further including, between and incontact with said dielectric sleeve and said outer shell, a semi-uid,conductive coating lconsisting essentially of silicone varnish, powderedgraphite and toluol.

References Cited in the le of this patent UNITED STATES PATENTSRe.21,926 Bormann- Oct. 2l, 1941 2,335,041 Bruno Nov. 23, 1943 2,379,942Webber ,J'uly 10, 1945 2,389,705 Wetzel Nov. 27, 1945 2,399,314 Barkeret al Apr. 30, 1946 2,422,982 Quackenbush June 24, 1947 2,457,796 WhiteDec. 28, 1948 2,473,570 Chirelstein June 21, 1949 2,642,474 Bowar June16, 1953

